PURPOSES : This study aimed to examine the relationship between discomfort glare and different types of lighting, including low-mounted lighting and conventional pole lighting. Although roadway lighting has been widely acknowledged as a countermeasure for nighttime traffic safety, discomfort glare, which is incidentally derived from lighting, is one of the key elements to overcome. METHODS : We selected the Unified Glare Rating (UGR), defined as a globally accepted lighting standard, as a measure of the effect of discomfort glare. Artificial rain and fog conditions were reproduced at the Center of Road Weather Proving Ground (CRPG). RESULTS : As a result, we found that the UGR of low-mounted lighting is reduced by 57.96% compared to pole lighting under rainy conditions, and by 39.12% in the case of fog conditions. CONCLUSIONS : It is proposed that discomfort glare was significantly reduced in the case of low-mounted lighting compared to pole lighting under both rain and fog conditions. Discomfort glare hinders the visual performance of drivers, so it may be related to delayed reaction time and inappropriate driving behavior. Therefore, low-mounted lighting is strongly recommended on road sections that have a high frequency of traffic accidents and adverse weather patterns.

PURPOSES : In this study, the relationship between the types of road pavement markings and the visibility distance under adverse weather conditions was evaluated. METHODS : Rainy and foggy conditions at the weather proving ground were replicated in this study. The researchers recorded the visibility distance corresponding to each experiment scenario comprising the weather conditions and pavement marking types. RESULTS : Visibility distances under adverse weather conditions decreased more than those of normal weather conditions. Under rainy conditions, the average visibility distance across all pavement markings decreased by 33%. However, the average visibility distance across all pavement markings foggy conditions decreased by 46.8%. Based on the test results of the visibility distance, the speed reduction rates corresponding to the adverse and normal weather conditions, i.e., 24% and 36% speed reduction under rainy and foggy conditions, respectively, were established. CONCLUSIONS : This study validated the reduction in the visibility distance affected by weather conditions by applying actual road scale weather proving ground. In addition, speed reduction was recommended for safe driving under adverse weather conditions.

PURPOSES : The purpose of this study is to analyze the impact of the level of the light-environment and the driver's visual ability on the change in the driver's perception of a forward curved section at night. The study also aims to identify factors that should be considered to ensure safety while entering curved sections of a road at night. METHODS : Data collected from a virtual driving experiment, conducted by the Korean Institute of Construction Technology (2017), were used. Logistic regression was applied to analyze the effects of changes in the light-environment factors (road surface luminance and glare) and the driver’s visual ability on a driver's perception of the road. Additionally, analysis of the moderated effect of visual ability on light-environment factors indicated that the difference in drivers’ visual abilities impact the influence of light-environment factors on their perception. A driver's ability to perceive, as a response variable, was categorized into 'failure' and 'success' by comparing the perceived distance and minimum reaction sight distance. Covariates were also defined. Road surface luminance levels were categorized into 'unlit road surface luminance' (luminance ≤ 0.1 nt) and 'lit road surface luminance' (luminance > 0.1 nt), based on 0.1 nt, which is the typical level observed on unlit roads. The glare level was categorized as 'with glare' and 'without glare' based on whether the glare was from a high-beam caused by an oncoming vehicle or not. The driver's visual ability level was categorized into 'low visual ability' (age ≥ 50) and 'high visual ability' (age ≤ 49), considering that after the age of 50, the drive’s visual ability sharply declines. RESULTS : The level of road surface luminance, glare, and driver's visual ability were analyzed to be significant factors that impact the driver's ability to perceive curved road sections at night. A driver's perception was found to reduce when the road surface luminance is very low, owing to the lack of road lighting ('unlit road luminance'), when glare is caused by oncoming vehicles ('with glare'), and if the driver's visual ability level is low owing to an older age ('low visual ability'). The driver's ability to perceive a curved section is most affected by the road surface luminance level. The effect is reduced in the order of glare occurrence and the driver's visual ability level. The visual ability was analyzed as a factor that impacts the intensity of the effect of change of the light-environment on the change of the driver's ability to perceive the road. The ability to perceive a curved section deteriorates significantly in 'low visual ability' drivers, aged 50 and above, compared to drivers with 'high visual ability,' under the age of 49, when the light-environment conditions are adverse with regard to the driver’s perception (road surface luminance: 'lit road surface luminance'→'unlit road surface luminance,' glare: 'without glare'→'with glare'). CONCLUSIONS : Supplementation, in terms of road lighting standards that can lead to improvements in the level of light-environment, should be considered first, rather than the implementation of restrictions on the right of movement, such as restricting the passage of low visual ability or aging drivers who are disadvantageous in terms of gaining good perception of the road at night. When establishing alternatives so that safety on roads at night is improved, it is necessary to consider improving drivers' perception by expanding road lighting installation. The road lighting criteria should be modified such that the glare caused by oncoming traffic, which is an influential factor in the linear change in perception, and the level of light-environment thereof are improved.

도로조명은 야간 운전자의 전방 시인성을 확보해 주어 안전운전이 가능하도록 하는 대표적 공공 사회 기반 시설이다. 전통적 도로조명인 폴 형태의 가로등은 광원과 노면의 높이차로 인한 구조적･성능적 한계 로 야간 시인성(안전) 확보의 최소 근거인 도로 조명 성능 기준 만족 및 악천후 시 시인성 확보(선형 및 위험요소, 차선확인 등)가 근본적으로 불가하다. 이러한 폴 가로등이 가지는 단점을 획기적으로 개선한 낮은 조명 시스템은 광원 높이 및 적용 광학계의 한계로 등기구 가격 상승 및 도로 조명 기준 만족을 위한 설치 간격조밀화를 수반하여, 가격 경쟁력 측면에서 불리하여 시장 진입 확대에 난항을 겪고 있다. 따라 서, 기존 낮은 조명시스템의 개선을 통해 가격 경쟁력 및 악천후 대응력을 추가로 확보하고, 이와 더불어 전 세계적 이슈로 부각되고 있는 에너지, 환경 문제 대응을 위한 에너지 자립 고성능･저가격의 조명 시스 템 개발이 필요한 실정이다. 이에 본 연구에서는 기존 개발 낮은 조명시스템의 광학계 및 재료･기구적 개 선을 통해 가격 경쟁력 및 안개 등 악천후 시 시인성 성능을 확보하고, 태양광 기반 전력 공급시스템 충전 효율성 및 전력 공급 안정성, 장수명을 확보하기 위한 기술을 개발·적용한 그림 1과 같은 악천후 대응 에너지 독립형 낮은조명 시스템을 개발하여 낮은 조명 시스템의 경쟁력을 확보하고자 한다. 본 연구의 핵심 기술은 첫째, 저가격, 고효율 낮은 조명 기술개발, 둘째, 야간 악천후 대응 최적 시인성 확보 기술 개발, 셋째, 태양광 기반 에너지 자립형 전력 공급기술 개발로서 체계적이고 효율적인 연구 및 테스트, 검·인증 과정을 거쳐 국내･외 시장에 확대･보급하는 것을 목표로 한다. 향후 본 연구의 성과를 활용한다면 안개 상습 취약 구간과 같이 악천후 대응이 필요한 구간 및 교량, 인터체인지 등 높은 조명의 구조적 안정성 확보가 어려운 구간에 활용이 가능하며, 국내 도로조명의 패러 다임 변환으로 도로조명분야 신시장 창출이 가능할 것으로 기대된다.

악천후 관련 대형 추돌사고 및 빗길 대형사고가 반복적으로 발생하고 있다. 특히 최근 기후변화에 따른 악천후 발생 빈도가 높아지고 있어 시급한 대책이 필요하다. 현행 도로교통법에 따라 악천후에는 감소의 무를 규정하고 있으나 운전자 스스로 기상상황에 맞추어 적정 속도로 주행하는 것은 어려움이 있다. 따라 서, 교통관리 운영자가 기상조건을 정확하게 검지하고 도로 및 기상상황에 따라 적정 제한속도를 표출해 주는 것이 필요하지만 현재 영종대교 시범운영구간을 제외하고는 국내 적용이 없는 실정이다. 본 연구는 악천후 시 기상조건을 정확하게 검지하고 도로상황을 감안한 제한속도를 표출하는 능동형 속도관리시스템을 개발하는 것이다. 능동형 속도관리시스템의 구성은 크게 기상검지기, 표출시스템, 속도 관리 전략 및 알고리즘으로 구성된다. 기상검지기는 눈, 비, 안개, 바람, 노면온도 등을 검지할 수 있도록 설계하고 저비용 보급형 실현을 위해 통합형 기상검지기 개발을 목표로 한다. 시인성 향상 표출부는 야간 및 악천후에도 시인이 가능한 수준의 휘도를 확보하기 위한 기술개발을 목표로 하고, 운영전략은 도로 및 기상상황에 따른 적정 제한속도 선정 및 교통류를 감안한 운영전략을 개발하는 것을 목표로 하고 있다. 본 연구가 완성되는 시점에서 기대효과로, 도로교통법에 규정된 악천후 시 감속 관련한 안전규정을 실 효성있게 도로현장에 적용될 수 있도록 하고, 이를 통해 악천후 시 운전자들에게 적정 제한속도를 표출함 으로써 운전자간 속도편차를 줄여 도로의 안전성을 향상시키고 교통류 흐름을 최대한 안정되게 유지할 수 있는 교통관리 효율화를 기대할 수 있다.